7s12p Samsung cells are capable of 120A continuous 240A surge but controllers are <30A and installed 40A fuse (trying new 58V fuses & holder)
Just finished 1, had to test drive it ... rain stopped for awhile.
No BMS installed! Turned out were only 20A continuous.
Mostly worried about parasitic draw when customers let set for the Winter.

10s2p Bricks disassembled into 8s2p + 2s2p and I was oh so tempted to build as 8s12p ... but needed for 24V bikes and I already have the 7s chargers.

25.9V 26.4Ah #2 nearly complete
Just need to run the parallels and power rails and install fuse.

High C-rate cells improve cold weather performance!

Samsung ICR18650-22p build is doing remarkably well in the colder weather!
There seems to be no noticeable deterioration in performance between the 70ºF weather of a couple weeks ago and the present 30-40ºF. Top speed stays in the 21mph range and acceleration seems the same.

The ICR prefix indicates Lithium Cobalt, same basic formulation as my previous laptop 18650 and LiPo builds (that suffered horribly from the cold) so I would have to attribute the cold weather performance "preservation" to the enhanced C rate of these Samsung cells.

Although the same basic formulation, additives, or some other alteration does shift the capacity map substantially!
LiCo laptop cells had capacity till about 3.70V while the Samsung cells map good capacity till 3.40V.
Sadly, this nixes my idea of combining cells, to hybrid the higher capacity laptop cells with the higher output Samsung cells.
While the Samsung would help output capability, a large percentage of it's capacity would be wasted, unless endangering or damaging the Laptop cells by excessive discharge.

A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

For my Snow Beast, eZip (24V 450w) volted up and geared down for 20mph@36V (675w). The Samsung cells seem very cold tolerant! 13.2Ah might not seem like much but great for my short Winter trips, nice for short spurts near 30mph if used on my cruiser eZips (Dual battery rack and switch allowing 25.9V on one side and 36V on the other). Just flip the switch for TURBO

A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

how you think these will do? think it's .5mm copper strip but will do them with some very thin foil at the connections to contour better.

can be stacked lengthwise or on top of each other with different copper strip that recesses better so nothing comes close when lengthwise or stacked. just 3d prints and copper pressed with another print and flexible tape. Will have to see how the tape holds it's compression.

its a super minimalist design for under a skateboard with minimal room

.
Tape protecting Positive\Negative interface on top of cell is a good idea.
Bonded solidly ... but to tape-cell's shrink wrap.
Advise wrap entire battery horizontally with duct tape to additionally stabilize Pos wire.
Fold Pos wire to exit at top, then duct tape? (provides "shock absorber" type protection for wire-connection)
Note - The term "battery" refers to a combined collection of items working together in cooperation..
EG An artillery battery is an assembly of guns.
Thus an electrical "battery" is a assembly of "cells".
A single cell is not appropriately considered a "battery"!.

Last edited by DrkAngel on Dec 25, 2017 1:28 am, edited 1 time in total.

A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

If I were you, I would add something to the corner of the 18650 can, plastic points card from any store, glue it onto the can in an L shape (upside down to protect the top and side), re glue wire, zip tie around, gorilla tape around just like the zip tie. Then proceed.

Yeah relooking, if you can shove a piece inbetween the wire, solder and can, you might not be able to.

Must reserve enough for my 750/1000w rear hub build, has switch for 750w "legal" and 1000w "TURBO".
Will build as 14s, as these Samsung cells have capacity till a static 3.40V.
(14s will hit 30mph+ in TURBO mode and will use streamlined posture and possible fairing to enhance speed-range)
So a 14s10p is doable with unassigned cells and I can "steal" another 60cells from 36V "alternate bag" if want larger ... or 2 smaller batteries.

Previous 9s12p eZip battery was constructed of re-recycled Sanyo laptop cells, with an actual ~20Ah capacity..
Used over the Winter on my 36V Snow Beast, it performed nicely, as long as I kept it warm ...

Ran it on my Comfort Cruiser over the Summer and pretty much finished it's useful life.
Cells were scavenged from previous builds >> from recycled laptop batteries = re-recycled.

33.3V 31.2Ah - 9s12p - Winter 2013-2014
2013 9s12p was constructed of 9 12 cell "bars"
2018 9s12p is constructed of NOS 12 cell laptop batteries in 4p segments, that stack nicely.
2p segments in top row were originally planned to be used as #9p, but realized will function much better by building 7-8-9p as 4x3 segments. I will swap 2 red (Sanyo) pairs to far right segment.

33.3V 31.2Ah - 9s12p - 2018

9s12p 2018.jpg (182.84 KiB) Viewed 1795 times

This build was planned as a replacement for my geared down volted up Snow Beast and for trips on my multivolt capable PA (Pedal Assist) and CC (Comfort Cruiser). Since original plan I've acquired a quantity of Samsung 36V hoverboard packs that perform much better than laptop cells in the cold. (Re-geared Snow Beast lower for 36V optimal performance!)

33V 31.2Ah @ 1038mAh will be dedicated for cruising with WOT restraint or traveling with 25mph+ PA capability.
With restraint, motor only could provide ~50 miles @18mph ... also have 33.3V 43Ah Cool Cell build I could carry for additional 70 miles.
But ... that is nearly 7 hours in the saddle ... ... might better push towards 23mph with recharging break.

Notable is that prolonged riding requires pedal assist to keep butt alive. On my Century run (100 eBike miles in 1 day) I had to re-position seat multiple times and take several walkabout breaks to make ride barely tolerable.

Future projects will include a convertible motorcycle type seat for comfort and more aerodynamic seating profile.

Last edited by DrkAngel on Jan 25, 2018 6:50 am, edited 1 time in total.

A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

Might be simplist build ever!
Note each 4 cell segment has a tab ... which can be folded over and soldered to my heavy tinned copper braid.
Also, I slid cardstock between cells and banding strips as additional safety measure.

solder tabs.jpg (147.49 KiB) Viewed 1621 times

I will build a small shelf to support masonite shelf over screw point.
Hot melt supporting formica.

shelf.jpg (35.34 KiB) Viewed 1621 times

Last edited by DrkAngel on Jan 25, 2018 6:50 am, edited 1 time in total.

A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

All cells were balanced charged, 1s72p for the Sony (green) and 1s36p on the Sanyo (red), more than a year ago.
All Sony @ 4.05 still within 1/100V of each other.
All Sanyo @ 4.04 still within 1/100V of each other.

Cells were all capacity tested (2016) and proved near 95% of rated, and with the proven minuscule, and equal, self discharge this looks to have the potential to be my best build yet.

At 32Ah, it will never exceed 1C discharge rate and will cruise at <.4C.
With moderated charged\discharged voltages, should be usable for many-many years!

Last edited by DrkAngel on Jan 25, 2018 6:51 am, edited 1 time in total.

A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

Finally finished 33.3V 31.2Ah eZip battery!
Naming MaxCell due to the 9s12p being the maximum number of cells that will physically fit in eZip RMB battery shell.
(And to differentiate from my 33.3V 43.2Ah insulated "Cool Cell")

Simple but very snug fit. To secure cells tightly and to protect solder points, top and bottom are covered with 1/8" closed cell foam sheets. Had to put a little weight on case to close properly ... center bows out a bit, center screw removed to allow 9s12p fit.

Side A was nice and straight forward, nice straight runs with heavy tinned copper braid.
Any connection over positive ends of cells were protected with additional HD duct tape!

Side A.jpg (186.61 KiB) Viewed 1483 times

Side B required a few curves, which was easy if braid curved before flattening.

Side B.jpg (199.85 KiB) Viewed 1483 times

Installed the new 58V rated fuse holder with 40A fuse. Upgraded charging wire to 18ga, unlikely to charge over 5A, will upgrade to 14ga if I ever want to charge at max recommended 15A.
Entire battery wrapped in clear boxing tape to stabilize and protect. Meter leads poke through easily, for testing.
Sides wedged firmly with sturdy cardboard.

Running short on the Samsung cells, deal is long gone, decided to save remaining intact 37V 4.4Ah BMSed for 36V projects, that leaves several eZip battery cases with SLA or worn out Lithium.
Might have found an extremely cheap, acceptable solution.

Thus, it seems important to use a charger, rather than a power supply.
The higher voltage, prolonged charge cycle must disconnect at some low current (charging amperage - mA) point.
Similar, somewhat, to SLA charging methodology ...
In fact, at least one manufacturer of LiFe batteries, Dakota, advises that their 4s (12V) battery can be charged with a typical 12V SLA charger.

Still working on LiFePO4 testing method.
LiFe has a very "tight" voltage capacity map.
and
seems to require some overpressure to "fill".

Charge-discharge testing the LiFePO4 ...
But I don't really like, or see the point in, discharging to the iMax LiFe "discharge" 2.00V!
So, with multiple iMax, I am charging to the 3.60V LiFe,
then discharging ti the LiIo 3.00V.

While LiFePO4 are rated as 3.65V - 2.00V, I feel:
Gentle cycling is better for breaking in and should still provide accurate comparative capacity.
5p @ 3 Amp = <.2C and I would rate as cells effectively "empty" @ 3.00V

Last edited by DrkAngel on Feb 25, 2018 8:57 pm, edited 1 time in total.

A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.